Oil Minister Murli Deora told reporters, "It is very unfortunate that our appeal to the oil sector officers' association has not been accepted by them."

Firms including Indian Oil, Oil and Natural Gas Corporation, Hindustan Petroleum Corporation Ltd (HPCL) and Oil India Ltd (OIL) will be affected by the strike.

The strike could have immediate impact on operations of refineries and aviation refuelling facilities, and a little later on oil and gas production.

Petroleum Secretary M S Srinivasan said a contingency plan for running key installations like oil and gas producing wells, refineries and aviation facilities with the help of Territorial Army has been put in place. The state governments had been asked to provide necessary support to prevent disruption of supplies.

The OSOA is demanding merging 50 per cent dearness allowance with basic pay, release of ad hoc payment and withdrawal of tax on perquisites like company-provided accommodation.

IOC chairman Sarthak Behuria said petrol and diesel supplies would be severely hit by the strike. “Retail outlets have stocks for 2-3 days, but a strike will trigger panic buying. Besides, refinery operations will be hit." He said the impact would be known on Wednesday.